An electronic apparatus such as a server or a personal computer is mounted with an electronic component such as a CPU (Central Processing Unit). When the electronic component generates heat exceeding its permissible temperature, the operation of the electronic component is no longer guaranteed, resulting in a failure in the electronic apparatus. In order to prevent such an occurrence, the server or the like is provided with a cooling device for cooling the electronic component.
The cooling devices are broadly categorized into an air-cooling type and a liquid-cooling type. Of these, the liquid-cooling type is advantageous over the air-cooling type in that the liquid-cooling type may efficiently cool the electronic component by quickly removing heat of the electronic component utilizing heat of vaporization of a coolant such as water.
The cooling device of the liquid-cooling type is provided with an evaporator for vaporizing the coolant by the heat of the electronic component.
The evaporator is provided with a bottom plate, and the electronic component comes in thermal contact with the bottom plate and thereby the electronic component is cooled by the heat of vaporization of the coolant in the evaporator. Then, it is desirable that the bottom plate be made as thin as possible to reduce thermal resistance of the bottom plate, in order to efficiently transfer the heat of the electronic component through the bottom plate to the coolant in the evaporator.
Further, to efficiently cool the electronic component, it is desirable that the coolant introduced into the evaporator be vaporized by the heat of the electronic component.
However, when the bottom plate of the evaporator is made thin as mentioned above, the bottom plate may decrease in strength and hence become deformed. Thus, the bottom plate is separated from the electronic component, so that the heat of the electronic component is no longer efficiently transferred to the evaporator.
Also, a condenser for condensing vapor of the coolant is connected to the evaporator; however, part of the coolant in the evaporator does not vaporize but returns to the condenser with its state remaining in liquid phase. Because of contributing little to the cooling of the electronic component, such a coolant becomes one of factors which decrease cooling efficiency of the evaporator.
Note that technologies related to the present application are disclosed in Japanese Laid-open Patent Publication Nos. 06-5754, 2008-218589, 2013-219165, 2002-168547, and 2013-243277.